1. Field of Invention
This invention relates to an improved pallet for packaging, material handling, shipping, and the like. More particularly, this invention relates to a pallet that is lightweight and preferably recyclable and durable as well.
2. Prior Art
Traditionally, pallets have been made of wood planks nailed together. In one common structure, a series parallel of upper wood planks are nailed to the top of three transversely extending, parallel, and equally-spaced wood support planks. Similarly, a series of parallel lower wood planks are nailed to the bottom of the three support planks.
Forklift forks can slide under the upper planks in the two parallel channels formed by the three spaced support planks. The forklift can then raise its forks, which lifts the pallet and anything mounted on it.
In an industrial packaging or shipping environment, wood pallets can withstand the often great abuses to which they are subject. The pallet may be dropped or rammed by a forklift or some other machine. The pallet may be slid around on a floor or stored outside in the rain or snow. It may be tossed around vigorously when being stored, stacked, or moved. A wood pallet can withstand a great deal of this type of use and abuse.
Wood pallets are, however, expensive, because they eventually breakdown. When they do, little of the wood is useable to make new pallets. To make new pallets, new wood is often required, which requires cutting down of further trees. This is not only expensive but of great environmental concern.
Wood pallets are also relatively heavy. Their weight increases the cost of storing or shipping products with them.
Wood pallets are also dangerous in that, wear and tear causes the wood to splinter and nails to become exposed. The splinters and exposed nails can damage the product being shipped as well as the human operators working with the pallets.
One attempt at a solution to the problems with wood pallets has been the paper pallet. The paper pallet can be made out of honeycomb paper components. The cellular honeycomb core provides remarkable compression strength, lightweight, and significantly improved cushioning ability over the wood pallet. Further, the paper components are totally recyclable as well as biodegradable. The paper pallet can thus be shredded, baled, and sold as recyclable paper, or alternatively returned to the environment through biodegrading.
One prior art paper pallet is made by International Honeycomb Illinois, Inc., 1149 Central Ave., University Park, Ill. 60466. This Honeycomb paper pallet is made of corrugated Kraft Honeycomb runners or blocks glued to the bottom of a corrugated Honeycomb pallet base or to the bottom of a corrugated cardboard carton. This paper pallet can weigh as little as 95% of the traditional wood pallets of a similar configuration. It also eliminates the need for nails and the problems that exposed nails and wood splinters can cause.
For pallets requiring fork access from only two opposing sides, the paper pallet can use three runners in parallel under the deck or carton. The three parallel runners form two parallel fork channels separated by the center runner. The forks from the forklift then penetrate the two fork channels to lift the pallet or carton.
In other forms of the prior art paper pallets, three parallel rows of three spaced apart paper honeycomb blocks are glued to the underside of a rectangular Honeycomb paper base. In this form, the forks can slide under the base form any of the four sides of the pallet. The three rows each form two channels for the forks on two opposing sides of the pallet, and the three lines of three spaced apart blocks form two transverse fork channels on the other two opposing sides of the pallet.
In yet another prior art paper pallet, called a "GMA" pallet, three parallel rows of three equally spaced Honeycomb paper blocks are glued to the underside of a rectangular paper Honeycomb base. One parallel paper Honeycomb runner is glued to the bottom of each row of blocks. In this manner, the blocks form channels for forks to penetrate and lift in the fork channels they provide intermediate the pallet base, which is glued to the topside of the blocks, and the runners, which are glued to the bottoms of the blocks.
Many of these types of paper pallets are remarkably strong. A standard four inch thick Honeycomb paper pallet made by International Honeycomb Corporation can safely carry a 2,500 pound load.
One problem with these prior art paper products is their significant sensitivity to moisture and humidity. Humidity significantly weakens the paper Honeycomb, and water contact can completely deform the paper Honeycomb and render it completely incapable of supporting any load at all.
One attempt to solve this problem involves coating the paper with polyethylene. The coating is relatively costly, however. It also frequently fails to provide the complete sealing required to keep moisture out of the paper. Particularly as the pallet is used and the forks or other activities erode the liner, leaks can occur, water can penetrate the leaks, and the Honeycomb paper pallet can become greatly weakened and ultimately even rendered useless.
Another problem with these paper pallets is their inherent weakness from damage to exposed sides of the Honeycomb paper runners or blocks. While the Honeycomb paper is remarkably strong in compression, it has very little bending strength. The Honeycomb side walls, which extend vertically, can withstand great compression forces (axially along their length), but relatively little bending force (directed transversely at the side walls of the Honeycomb). As a result, when a support runner or block is rammed in the side by the fork of a forklift as it often is in a shipping and handling environment, the paper Honeycomb is easily crushed and greatly weakened or even destroyed. Consequently, these types of paper pallets often are unacceptably costly not only because of the large numbers of pallets destroyed but also because of resulting damage to product being stored or shipped and the labor cost of fixing and repairing the damage to pallets and product.